The present invention relates to force adjusting devices, and more particularly relates to a force adjusting device that is easily adjustable to vary a biasing force, but that locks after adjustment to maintain an adjusted biasing force. Further, the present invention concerns a chair that incorporates the force adjusting device into an adjustable lumbar support arrangement on a back of the chair.
Force adjusting devices are sometimes used in mechanical assemblies to provide a biasing force to accomplish a desired result. A problem is that where significant biasing force is desired, these mechanisms can become expensive, unacceptably large in size, and unacceptably complex. Complexity can further result in quality and warranty problems. Another problem is that there often are conflicting requirements for such devices. For example, it is desirable to provide an adjusting motion that is easily accomplished, but that provides significant change in biasing force with only a small amount of adjustment effort and motion. Further, when used in retail consumer products, the adjusting motion must preferably operate smoothly and provide a luxurious feel to the user, while using low cost and easily assembled components. It is difficult to simultaneously achieve such a result. Still further, the adjusting motion must be intuitively obvious so that users will know how to adjust the device without having to read an instruction manual, yet the adjusting device must have an aesthetically acceptable appearance and only take up a minimum of space. Also, assembly of the force adjusting device to the component being biased preferably must be easily accomplished with low labor requirements.
Accordingly, a force adjusting device is desired that is reliable, relatively non-complex, solves the aforementioned problems, and has the aforementioned advantages.